from osgeo import ogr

def CheckPGDriver():
    ## PostgreSQL available?
    driverName = "PostgreSQL"
    drv = ogr.GetDriverByName( driverName )
    if drv is None:
        print "%s driver not available." % driverName
    else:
        print  "%s driver IS available." % driverName

def ListAllLayers():
    conn = ogr.Open(connString)
    layerList = []
    for i in conn:
        daLayer = i.GetName()
        if not daLayer in layerList:
            layerList.append(daLayer)
    layerList.sort()
    for j in layerList:
        print "Layer found:", j

def GetPGLayer( lyr_name ):
    conn = ogr.Open(connString)
    lyr = conn.GetLayer( lyr_name )
    if lyr is None:
        print '[ ERROR ]: layer name = "%s" could not be found in database "%s"' % ( lyr_name, databaseName )
    featureCount = lyr.GetFeatureCount()
    print "Number of features in %s: %d" % ( lyr_name , featureCount )

if __name__ == '__main__':

    CheckPGDriver()

    databaseServer = "localhost"
    databaseName = "snaps"
    databaseUser = "postgres"
    databasePW = "xxxxxxxx"
    knowntable = "plants.alias"
    connString = "PG: host=%s dbname=%s user=%s password=%s" %(databaseServer,databaseName,databaseUser,databasePW)

    ListAllLayers()
    GetPGLayer(knowntable)

/usr/bin/python2.7 /home/martin/Work_Pycharm/fun_misc/src/scan_that_db.py
PostgreSQL driver IS available.
Layer found: plants.sa_analyse
Number of features in plants.alias: 82

Process finished with exit code 0